Converting cast-iron into malleable iron or steel



(No Model.)

S. HUFTY 8v J. K. CALDWELL. GONVE'RTING GAST IRON INTO MALLEABLE IRON 0R STEEL.

No. 536,082. Patented Mar. 19,1895.

UNITED STATES l PATENT OEEICE.

SAMUEL HUFTY, OE CAMDEN, NEW JERSEY, AND JOSEPH K. CALDWELL,

OF PHILADELPHIA, PENNSYLVANIA. i

CONVERTING CAST-IRON INTO MALLEABLE IRON OR STEEL.

SPECIFICATION forming part of Letters Patent No. 536,082, dated March 19, 1895.

Application filed August 18. 1894. Serial No. 520,692. (No specimens.)

To all whom it may concern:

Be it known thatvwe, SAMUEL I-IUFIY, residing in Camden, New Jersey, and JOSEPH K. CALDWELL, residing in Philadelphia, Pennsylvania, citizens of the United States, have invented certain Improvements in Processes of Converting Cast-Iron into Malleable Iron or Steel, of which the following isa specification.

The object of our invention is to eifect the partial decarbonization of solid forms of cast iron in order to convert the same into malleable iron or steel, an object Which we attain in the manner hereinafter set forth, reference being had to the accompanying drawings, in which- Y l Figure 1,represents a longitudinal sectional View of a furnace adaptedfor the carrying out of our invention; and Fig. 2, represents a sectional plan view of the same.

Our invention consists essentially of a process comprising two steps, first, the bringing of the solid forms of cast iron to the required temperature by means of'a reducing llame, that is to say, a flame in which the oxygen is not present in volume necessary to cause complete combustion, and, secondly, in bringing into contact with the said solid forms of cast iron, after they have been properly heated and while they are maintained at the desired temperature by means of said reducing flame, a volume of oxygen largely in excess of that required to support the combustion of the heating flame, this excess of oxygen acting upon the highly heated carbon of the cast iron to oxidize the same and thereby effect a partial elimination of the carbon from the iron in the form of carbonic oxide, the treatment being continued until the decarbonization of the iron to the desired extent has been effected. The desired 'excess of oxygen is provided by means of jets of air or Water preferably heated, or by jets of steam, as hereinafter set forth.

In the drawings We have illustrated a form of furnace adapted to use liquid hydrocarbon as fuel, but it should be understood that coal, wood, coke or other fuel may be used instead ofA liquid hydrocarbon without departing from our invention, the hydrocarbon being preferred, however, on account of its greater convenience and eectiveness.

A represents an open hearth furnace provided withV suitable charging doors a and stack b for the discharge of the products of combustion, the furnace being also provided With a series of hydrocarbon burners d of any available construction, but preferably of that Iclass in-Which the hydrocarbon is permitted to flow from a valved pipefinto a moving current lof air, the volume and speed of which may be regulated by means of a valve g in the supply pipe, the hydrocarbon being atomized by the air current and issuing with the same from the discharge nozzle of the burner Y so as to act directly upon the solid forms of cast iron deposited upon the hearth of the furnace.

Each hydrocarbon burner passes through a tuyere opening z' in the wall of the furnace, which tuyere opening is closed at the outer end by means of a valved or dampered register plate m so that by properly adjusting the ivalve of said plate, air in regulated volume pipes or nozzles communicating with anyA available supply of air under pressure and the flow ofair through said pipes or nozzles being regulated by a suitable valve or series of valves, or, if desired, all of these different means of supplying air to the interior of the furnace may be adopted in one and the same structure, or instead of supplying air, the pipes or nozzles may supply jets of Water or steam, the water or air being by preference heated.

In carrying out our invention the solid forms of cast iron in the shape of pigs, bars, ingots or molded articles are'deposited upon the hearth of the furnace and the charging cpenings being closed, the flame from the burners d is directed upon the charge and is maintained until said charge becomes heated to the required temperature, which should be Several hundred degrees below the fusing IOO hearth of the furnace are ,closed so that no oxidation of the iron will be eifected during the heating of the same, it being understood that the flame from the burners d is simply a reducing flame. After the charge upon the hearth of the furnace has been heated to the required degree and while the reducing flame from the burners d is still acting upon the charge in order to maintain the heat ofthe same, the valves of the tuyere plates are opened, or air, steam or wateris forced into the furnace through the pipesn or norallof these sources of supply are utilized for the purpose of directing volumes of oxygen into contact with all parts of the heated charge upon the hearth of the furnace, the air, steam, or water being decomposed on contact with the surfaces of the highly heated forms of iron so as to set free the oxygen which combines With the carbon of the heated iron and causes the same to pass off in the form of carbonio oxide, experiment having demonstrated that when the iron is heated to a temperature approaching the point of fusion the oxygen will have a tendency to attack the carbon rather than the iron, as is evidenced by the fact that in the practical carrying out of our process a con siderable percentage of carbon can be removed from the iron without any material formation of oxide of iron scale upon the surfaces of the articles being treated. In fact, the formation of such an oxide scale would be fatal to the proper carrying out of our invention, since the scale acts in the nature of a seal and prevents access of the oxygen to the carbon in the metal. After the treatment has been continued for such a length of time as to effect the decarbonization of the iron to the desired extent, the burners d are shut off and the flow of air to the furnace discontinued, the articles being allowed to cool slowly until they are in condition to be removed preparatory to the introduction of a fresh charge. If a continuous flow of air,

water or steam into the furnace in such volume and with such force as to reach all portions of the charge contained therein, effects any material reduction of the temperature of the charge, the iiow may be stopped at intervals until the iame from -tl1e burners dagain brings the charge up to the desired temperature,

We are aware that it has been proposed to subject solid forms of cast iron upon the hearth of a furnace to a flame containing carbon, hydrogen and oxygen in quantity properly regulated to produce complete combustion and a homogeneous flame previous to the admission of said llame to the furnace chamber, but our invention diiers essentially from this in that it involves the employment of a reducing flame for heating and while said reducing Haine is still maintained the contact with the heated iron of a decomposable oxygen-bearing fiuid which by its decomposition supplies the oxygen necessary to attack and remove carbon from the iron.

We therefore claim and desire to secure by Letters Patent- The mode herein described of treating solid forms of cast iron for the purpose of converting the same into malleable iron or steel, said mode consisting in rst heating said articles in an open hearth furnace by a reducing llame to a temperature somewhat below fusion and, afterthe iron has reached the desired temperature and while it is still subjected to the action of said reducing flame, bringing into direct contact with the iron a decomposable oxygen-bearing1 fluid in such volume that by its decomposition oxygen is freed in volume sufficient to combine with and eliminate carbon from the heatediron, substantially as specied.-

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

SAMUEL HUFTY. JOSEPH K. CALDWELL. lVitnesses:

- WILLIAM A. BARR, J osEPH H. KLEIN. 

